How popular is Darlina?

Darlina is an uncommon given name for women. Darlina is also a rare surname for all people. (2000 U.S. Census)

Which version is better?

with its source form and related girl names. Darla(#1682 via latest list), Darleen, Darlena, Darlene(#1443), Darline and Darlyne are the prominent related forms of Darlina (outside Top 2000). These forms of Darlina were favored 65 years ago (average #1001) and have become much less common since, with versions like Darla becoming less stylish. (Top Baby Names, 2015)